With development of mobile terminals and data services, demand for data service traffic increases massively. To meet the soaring traffic demand, small cells may be deployed in hotspot areas based on a conventional macro cellular network. A small cell has small coverage and low transmit power, and can provide a high-rate data transmission service, so as to perform data offloading for a macro cellular network and reduce network deployment costs of an operator. Forms of a small cell include: a metropolitan cell Metro cell, a micro cell Micro cell, a pico cell Pico cell, a home NodeB, Femto cell, and a WLAN (Wireless Local Area Network) using a Wi-Fi (Wireless Fidelity) technology. Each small cell may be deemed a transmitting/receiving node.
After a group of nodes are deployed in the foregoing manner, time synchronization needs to be performed for the group of nodes, so as to implement technologies such as dynamic switching of a cell and dual connectivity for a user after the synchronization and improve network operation efficiency. An existing timing synchronization method includes: determining a time-synchronized node as a synchronization source, and implementing, by a to-be-synchronized node, time synchronization by receiving a synchronization signal of the synchronization source node.
At least the following problem exists in the prior art: In the foregoing synchronization process, the to-be-synchronized node needs to receive information from the synchronization source node, but the to-be-synchronized node may not be capable of receiving the information sent by the synchronization source node. For example, in an FDD (Frequency Division Duplex) system, if the to-be-synchronized node and the synchronization source node have a same operating frequency, a synchronization reference signal sent by the synchronization source node can be sent only on a downlink frequency, but the to-be-synchronized node is generally not capable of receiving on a downlink frequency. Similarly, in a TDD (Time Division Duplex) system, if the to-be-synchronized node and the synchronization source node have different operating frequencies, the to-be-synchronized node is generally not capable of receiving a signal on an operating frequency of the synchronization source node either.